Several authors^{[1][2][3][4][5]} have reported a presumed post encephalitic catastrophic epileptic encephalopathy resulting in refractory repetitive seizures associated with severe cognitive impairment.

Mikaeloff et al^[3] in 2006 described this condition in a retrospective study of normally developing 14 children (mean age 7.5yrs) admitted with prolonged status epilepticus following a nonspecific febrile illness and called it Devastating Epileptic encephalopathy in School-age Children (DESC).

The current term febrile infection-related epilepsy syndrome (FIRES) was proposed by Van Baalen et al^[6] in 2010 who published a retrospective multicenter case series of 22 previously healthy children aged 3-15yrs (largest of the series) who developed prolonged and recurrent refractory seizures occurring 2-14 days (median 5 days) after fever onset.

Absence of either encephalitic changes in neuroimaging,marked CSF leukocytosis or inflammatory changes on biopsy suggests that the pathological process is not one of inflammation. The clinical course is characterised by intractable recurrent/prolonged seizures suggesting neuronal hyperexcitation as the underlying cause.It is possible that the pathogenesis is immune mediated.

• The condition occurs in previously healthy normally developing children aged 3-15 years.
• Characterised by an acute convulsive status epilepticus following a short febrile episode without any evidence of cns infection or inflammation.
• The status epilepticus is highly pharmacoresistant and can persist for more than a month
• The seizures are characteristically bilateral perisylvian with propagation to the frontal lobes and are extremely frequent and refractory
• The acute phase is followed by a chronic pharmacoresistant epilepsy associated with severe cognitive impairment mainly involving language, memory and behaviour.
• There is no latent period between the progression from acute to chronic phase.

• EEG shows diffuse slowing or multifocal discharges
• Extreme delta brush (EDB) in the background is frequently seen in the acute presentation^[7]
• prolonged focal fast activity and hemispheric shifting ictal activity is characteristic and is a potential early biomarker in patients with FIRES^[7]

Ictal shifting: The seizure begins in the left occipital region with spread to the left hemisphere. Twenty seconds later, there is ictal activity in the right frontal region with subsequent spread to the entire right hemisphere. The seizure continues to the right hemisphere after the left‐hemisphere seizure ends. Red: Left‐sided electrodes, Blue: Right‐sided electrodes, Black: vertex electrodes, and electrocardiogram.(Farias‐Moeller et al.2017)

Extreme delta brush on a bipolar montage(Farias‐Moeller et al.2017)

Typical seizure pattern with focal fast activity preceding spikes or spike/wave complexes on a referential montage.(Farias‐Moeller et al.2017)

Neuroimaging

Plain MRI is often normal, although selective bilateral hippocampal abnormalities including atrophy and hypersignal have been reported.18F-FDG PET studies^[8] have shown widepsread interictal hypometabolic network including the temporoparietal and orbitofrontal cortices bilaterally. The hypometabolic areas corresponded to the electroclinical seizures involving the temporofrontal cortex bilaterally as well as to the neuropsychologic findings.

Neuropsychology

FIRES and NORSE

Treatment